EP0148389B1 - Tuning system for a television receiver - Google Patents

Tuning system for a television receiver Download PDF

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Publication number
EP0148389B1
EP0148389B1 EP84114292A EP84114292A EP0148389B1 EP 0148389 B1 EP0148389 B1 EP 0148389B1 EP 84114292 A EP84114292 A EP 84114292A EP 84114292 A EP84114292 A EP 84114292A EP 0148389 B1 EP0148389 B1 EP 0148389B1
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Prior art keywords
frequency
tuner
carrier frequency
microprocessor
component
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EP84114292A
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German (de)
French (fr)
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EP0148389A3 (en
EP0148389A2 (en
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Gerhard Maier
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Deutsche Thomson Brandt GmbH
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Deutsche Thomson Brandt GmbH
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Priority to AT84114292T priority Critical patent/ATE50894T1/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control

Definitions

  • the invention relates to an automatically working adjustment system for the tuner of a television receiver with a tunable oscillator tunable by a phase locked loop, in which an auxiliary frequency is switched on to the antenna input during the automatic adjustment and the individual HF tuning circuits of the tuner are successively adjusted to a maximum output voltage , controlled by a microprocessor successively in digital steps tuning voltage values to those in the RF tuning circuits. located capacitance diodes and the increase in the tuning voltage values is interrupted when a maximum value determined by an evaluation circuit is reached at the output.
  • Such a tuning unit is e.g. B. described in DE-A-28 54 852, which tune the high-frequency circuits to the desired reception frequency by means of three auxiliary oscillators and associated analog memories using the PLL circuit.
  • the tuner oscillator is also used for the adjustment.
  • auxiliary oscillators corresponding to the number of high-frequency circuits to be adjusted are necessary. The number of auxiliary oscillators required and thus the cost of materials increases particularly if, for. B. when comparing a television receiver volume I, volume 111 and bands IV and V are to be compared. There is a risk of ambiguity between the frequencies of the tuner oscillator, the auxiliary oscillators and the reception frequencies.
  • a disadvantage of a practical implementation of the proposed tuning unit is that the excitation windings of the auxiliary oscillators with the individual coils in the high-frequency circuits can cause undesirable resonances and damping of the circuits, which also cause an uncontrollable detuning of the circuits if the auxiliary oscillators are switched off after the adjustment has taken place.
  • Analog memories are also provided, which must be reloaded at intervals in order to obtain the optimal tuning values. For these reasons, due to the principle, an optimal adjustment of the receiving device cannot be achieved. In addition, the repetitive repetition makes repetitions visible or audible on the screen or in the speaker.
  • a test system for a receiver is also known (US-A-3736512, which checks the properties of the individual stages of the receiver such as, for example, preamplifier, mixing stage, IF amplifier in on-line operation. which are visually displayed, must be corrected by the operator of the receiver It is not a self-contained adjustment system in which RF filter circuits are automatically adjusted optimally for each receiving channel.
  • the invention has for its object to provide a matching system, which automatically selects the message receiving device by selecting a channel, in which the RF filters are brought to optimal values. This object is achieved by the invention specified in the patent claim.
  • the invention has the advantage that, by utilizing the integrated intermediate frequency module, which is already present in the message receiving device, with its typical amplification of 60 db, an exact evaluation of the measurement voltage is possible even for the smallest level of the auxiliary oscillator frequency. Costs are saved with the highest sensitivity of the automatic adjustment. Due to the low level of the auxiliary oscillator frequency at the antenna input, the postal regulations regarding interference radiation are met with certainty.
  • a tuner of a message receiving device is denoted by 1, the HF filter circuits 2, 3 and 4 of which are to be automatically adjusted by applying matching DC voltages to the capacitance diodes located in them.
  • a mixing stage 6 is switched on via a switching stage 7 controlled by a microprocessor 5.
  • the mixer stage With the help of an auxiliary oscillator 8, the mixer stage generates a characteristic frequency, which reaches the antenna input of tuner 1 via capacitor 9.
  • the auxiliary frequency generated by the mixer 6 is derived from the oscillator frequency f osc of the tuner oscillator which is controlled by a phase-locked loop 11, 12, and from the frequency of the local oscillator 8 as a difference frequency of f osc - is f Hilf, In Germany Frequency then always between the HF picture and HF sound carrier. So there is z. B. when selecting channel 10 in band 111 of TV reception frequency range a characteristic frequency of 213 MHz with a set oscillator frequency of 249.15 MHz of the tuner oscillator 1.
  • the characteristic frequency of 213 MHz together with the oscillator frequency of 249.15 MHz results in an intermediate frequency of 36.15 MHz at the output of the tuner 1.
  • This intermediate frequency lies in the middle of the band of the intermediate frequency channel and reaches the intermediate frequency module 14 present in the receiving device via a bandpass 13.
  • This module has a synchronous demodulator for which the reference frequency is generated at an externally connected reference resonant circuit 15.
  • the reference resonant circuit consists of the capacitor 16 and the coil 17 and is tuned to 38.9 MHz for intermediate reception, the intermediate image frequency carrier.
  • the reference resonant circuit 15 is switched to the lower reference frequency 36.15 MHz, controlled by the microprocessor 5, in that a capacitor 19 is connected in parallel via the switching stage 18.
  • a measuring voltage is taken from the capacitor 20, which is converted via a sample-and-hold circuit 21 and fed to the microprocessor, which increases the tuning voltage until a maximum of the measuring voltage at the AGC output is reached.
  • the microprocessor increases the tuning voltage in stages via the D / A converter 23 until the S / H circuit indicates an optimal adjustment. A digital word is stored for this optimal comparison.
  • the other circles are controlled in succession in the same way by the microprocessor 5. It is necessary to reduce the time constant of the automatic gain control during the automatic adjustment. This is done by switching off the capacitor 25, which is relevant for a large time constant, via a switching stage 24.
  • the tuner oscillator frequency is set to 249.15 MHz.
  • the image carrier of the received signal is 210.25 MHz and the sound carrier is 215.75 MHz.
  • a characteristic frequency K is generated which lies between the image carrier and the sound carrier and which is 36.15 MHz lower than the set oscillator frequency. This frequency K thus represents the difference between free and 36.15 MHz.
  • Fig. 3 it is shown how the reference circuit 15 is switched from its resonance frequency 38.9 MHz to 36.15 MHz.
  • FIG. 4 shows the course of the AGC voltage, which is an exact image of the reference circuit according to FIG. 3.

Abstract

1. An adjustment system working automatically for the tuner of a television receiver having a tuner oscillator (10) which can be tuned by a phase-locked loop (PLL), wherein an auxiliary frequency (8) is connected to the aerial input during the automatic adjustment and the individual radio-frequency tuned circuits (2, 3, 4) of the tuner (1) are adjusted in succession to a maximum output voltage in that tuning voltage values are applied in succession, in digital steps, controlled by a microprocessor (5), to the capacitance diodes present in the radio-frequency tuned circuits (2, 3, 4), and the increase in the tuning voltage values is interrupted when a maximum value, detected by an evaluation circuit, is reached at the output, characterised in that a frequency which results from the difference between the set tuner oscillator frequency (OSC) and the arithmetical mean of the i.f. picture-carrier frequency (BT) and the sound-carrier frequency (TT) is selected as the auxiliary frequency (K), that during the automatic adjustment operation, the i.f. component (14) present in the set is used as an evaluation circuit in that the output signal for the automatic gain control (AGC) is fed as a measuring voltage to a sample-and-hold circuit (21) which is connected to an input of the microprocessor (5), and that the reference oscillatory circuit necessary in the i.f. component (14) is switched over, in its resonant frequency to a frequency which corresponds to the arithmetical mean of i.f. picture-carrier frequency (BT) and i.f. sound-carrier frequency (TT).

Description

Die Erfindung geht aus von einem automatisch arbeitenden Abgleichsystem für den Tuner eines Fernsehempfangsgerätes mit einem von einem Phasenregelkreis abstimmbaren Tuneroszillator, bei welchem während des automatischen Abgleichs an den Antenneneingang eine Hilfsfrequenz angeschaltet ist und die einzelnen HF-Abstimmkreise des Tuners nacheinander auf eine maximale Ausgangsspannung abgeglichen werden, indem von einem Mikroprozessor gesteuert nacheinander in digitalen Schritten Abstimmspannungswerte an die in den HF-Abstimmkreisen. befindlichen Kapazitätsdioden gelegt werden und die Erhöhung der Abstimmspannungswerte bei Erreichen eines durch eine Auswerteschaltung festgestellten Maximalwertes am Ausgang unterbrochen wird.The invention relates to an automatically working adjustment system for the tuner of a television receiver with a tunable oscillator tunable by a phase locked loop, in which an auxiliary frequency is switched on to the antenna input during the automatic adjustment and the individual HF tuning circuits of the tuner are successively adjusted to a maximum output voltage , controlled by a microprocessor successively in digital steps tuning voltage values to those in the RF tuning circuits. located capacitance diodes and the increase in the tuning voltage values is interrupted when a maximum value determined by an evaluation circuit is reached at the output.

Eine derartige Abstimmeinheit ist z. B. in der DE-A-28 54 852 beschrieben, die mittels dreier Hilfsoszillatoren und diesen zugeordneten Analogspeichem unter Verwendung der PLL-Schaltung die Hochfrequenzkreise auf die gewünschte Empfangsfrequenz abstimmen. Bei dieser Abstimmeinheit wird auch dabei der Tunersozillator beim Abgleich herangezogen. Außerdem sind der Zahl der abzugleichenden Hochfrequenzkreise entsprechende Hilfsoszillatoren notwendig. Die Zahl der benötigten Hilfsoszillatoren und somit der Materialaufwand erhöht sich dann in besonderem Maße, wenn z. B. beim Abgleich eines Fernsehempfängers Band I, Band 111 und die Bänder IV und V abgeglichen werden sollen. Es besteht dabei die Gefahr von Mehrdeutigkeiten zwischen den Frequenzen des Tuneroszillators, der Hilfsoszillatoren und den Empfangsfrequenzen. Nachteilig für eine praktikable Realisierung der vorgeschlagenen Abstimmeinheit ist, daß die Erregerwicklungen der Hilfsoszillatoren mit den einzelnen Spulen in den Hochfrequenzkreisen unerwünschte Resonanzen und Bedämpfungen der Kreise hervorrufen können, die auch noch eine unkontrollierbare Verstimmung der Kreise verursachen, wenn die Hilfsoszillatoren nach erfolgtem Abgleich abgeschaltet sind. Außerdem sind Analogspeicher vorgesehen, die in zeitlichen Abständen nachgeladen werden müssen, um die optimalen Abstimmwerte zu erhalten. Aus diesen Gründen ist prinzipbedingt ein optimaler Abgleich des Empfangsgerätes nicht erreichbar. Außerdem werden durch das sich laufend wiederholende Nachstimmen Störungen auf dem Bildschirm oder im Lautsprecher sichtbar bzw. hörbar.Such a tuning unit is e.g. B. described in DE-A-28 54 852, which tune the high-frequency circuits to the desired reception frequency by means of three auxiliary oscillators and associated analog memories using the PLL circuit. With this tuning unit, the tuner oscillator is also used for the adjustment. In addition, auxiliary oscillators corresponding to the number of high-frequency circuits to be adjusted are necessary. The number of auxiliary oscillators required and thus the cost of materials increases particularly if, for. B. when comparing a television receiver volume I, volume 111 and bands IV and V are to be compared. There is a risk of ambiguity between the frequencies of the tuner oscillator, the auxiliary oscillators and the reception frequencies. A disadvantage of a practical implementation of the proposed tuning unit is that the excitation windings of the auxiliary oscillators with the individual coils in the high-frequency circuits can cause undesirable resonances and damping of the circuits, which also cause an uncontrollable detuning of the circuits if the auxiliary oscillators are switched off after the adjustment has taken place. Analog memories are also provided, which must be reloaded at intervals in order to obtain the optimal tuning values. For these reasons, due to the principle, an optimal adjustment of the receiving device cannot be achieved. In addition, the repetitive repetition makes repetitions visible or audible on the screen or in the speaker.

In der Zeitschrift « Nachrichten elektronik » Heft 11/79, Seiten 365-368 wird ein Abstimmverfahren für Rundfunkempfänger beschrieben, das ebenfalls zusätzliche Hilfskreise in den Hochfrequenzfiltem anwendet. Auch hier ergeben sich nachteilige Beeinflussungen der Kreise im Betrieb des abgeglichenen Empfängers. Wie auf Seite 367 linke und mittlere Spalte angegeben, wird die Genauigkeit der Abstimmungen durch Spezialbauteile nur in Form von exakt gepaarten Dioden erzielt. Auch dies erfordert einen nicht außer acht zu lassenden Aufwand.In the magazine "Nachrichten elektronik", issue 11/79, pages 365-368, a voting procedure for radio receivers is described, which also uses additional auxiliary circuits in the high-frequency filters. Here, too, the circles are adversely affected in the operation of the matched receiver. As indicated on page 367 left and middle column, the accuracy of the tuning is only achieved with special components in the form of exactly paired diodes. This also requires an effort that cannot be ignored.

Es ist auch ein Testsystem für einen Empfänger bekannt (US-A-3736512, welches im On-line-Betrieb die Eigenschaften der einzelnen Stufen des Empfängers wie z. B. Vorverstärker, Mischstufe, ZF-Verstärker überprüft. Bei Abweichungen von den Sollwerten, die optisch angezeigt werden, müssen diese vom Bedienenden des Empfängers korrigiert werden. Es handelt sich nicht um ein in sich geschlossenes Abgleichsystem, bei welchem HF-Filterkreise automatisch für jeden Empfangskanal optimal abgeglichen werden.A test system for a receiver is also known (US-A-3736512, which checks the properties of the individual stages of the receiver such as, for example, preamplifier, mixing stage, IF amplifier in on-line operation. which are visually displayed, must be corrected by the operator of the receiver It is not a self-contained adjustment system in which RF filter circuits are automatically adjusted optimally for each receiving channel.

Der Erfindung liegt die Aufgabe zugrunde, ein Abgleichsystem zu schaffen, welches bei Anwahl eines Kanals vollkommen automatisch das Nachrichtenempfangsgerät abgleicht, in dem die HF-Filter auf optimale Werte gebracht werden. Diese Aufgabe wird durch die im Patentanspruch angegebene Erfindung gelöst.The invention has for its object to provide a matching system, which automatically selects the message receiving device by selecting a channel, in which the RF filters are brought to optimal values. This object is achieved by the invention specified in the patent claim.

Die Erfindung besitzt den Vorteil, daß durch die Ausnutzung des ohnehin im Nachrichtenempfangsgerät vorhandenen integrierten Zwischenfrequenzbausteins mit seiner typischen Verstärkung von 60 db selbst für kleinste Pegel der Hilfsoszillatorfrequenz eine exakte Auswertung der Meßspannung möglich ist. Es werden Kosten gespart bei höchster Empfindlichkeit des automatischen Abgleichs. Durch die niedrigen Pegel der Hilfsoszillatorfrequenz am Antenneneingang werden die Postvorschriften bezüglich Störstrahlung mit Sicherheit eingehalten.The invention has the advantage that, by utilizing the integrated intermediate frequency module, which is already present in the message receiving device, with its typical amplification of 60 db, an exact evaluation of the measurement voltage is possible even for the smallest level of the auxiliary oscillator frequency. Costs are saved with the highest sensitivity of the automatic adjustment. Due to the low level of the auxiliary oscillator frequency at the antenna input, the postal regulations regarding interference radiation are met with certainty.

Nachstehend soll an einem Ausführungsbeispiel das Wesentliche des angemeldeten automatischen Abgleichsystems mit Hilfe der Zeichnung beschrieben werden.

  • Fig. 1 zeigt die wesentlichen für das automatische Abgleichsystem erforderlichen Baugruppen in einem Blockschaltbild.
  • Fig. 2 bis 4 zeigen zur Erläuterung der Wirkungsweise der Schaltung nach Fig. 1 dienende Diagramme.
The essence of the registered automatic adjustment system will be described below with the aid of the drawing using an exemplary embodiment.
  • 1 shows the essential assemblies required for the automatic adjustment system in a block diagram.
  • 2 to 4 show diagrams used to explain the mode of operation of the circuit according to FIG. 1.

in Fig. 1 ist ein Tuner eines Nachrichtenempfangsgerätes mit 1 bezeichnet, dessen HF-Filterkreise 2, 3 und 4 automatisch abgeglichen werden sollen, indem an die in diesen befindlichen Kapazitätsdioden entsprechende Abstimmgleichspannungen angelegt werden. Beim automatischen Abgleich wird über einen Mikro-Prozessor 5 gesteuert eine Mischstufe 6 über eine Schaltstufe 7 eingeschaltet. Die Mischstufe erzeugt mit Hilfe eines Hilfsoszillators 8 eine Kennfrequenz, die über den Kondensator 9 an den Antenneineingang des Tuners 1 gelangt. Die von der Mischstufe 6 erzeugte Hilfsfrequenz ergibt sich aus der Oszillatorfrequenz fosc des Tuneroszillators, der von einer PLL-Schleife 11, 12 geregelt wird, und aus der Frequenz des Hilfsoszillators 8 als Differenzfrequenz aus fosc- fHilf, In Deutschland befindet sich diese Frequenz dann immer zwischen dem HF-Bild- und HF-Tonträger. So ergibt sich z. B. bei Anwahl des Kanals 10 im Band 111 des Femsehempfangsfrequenzbereichs eine Kennfrequenz von 213 MHz bei einer eingestellten Oszillatorfrequenz von 249,15 MHz des Tuneroszillators 1.In Fig. 1, a tuner of a message receiving device is denoted by 1, the HF filter circuits 2, 3 and 4 of which are to be automatically adjusted by applying matching DC voltages to the capacitance diodes located in them. In the case of automatic adjustment, a mixing stage 6 is switched on via a switching stage 7 controlled by a microprocessor 5. With the help of an auxiliary oscillator 8, the mixer stage generates a characteristic frequency, which reaches the antenna input of tuner 1 via capacitor 9. The auxiliary frequency generated by the mixer 6 is derived from the oscillator frequency f osc of the tuner oscillator which is controlled by a phase-locked loop 11, 12, and from the frequency of the local oscillator 8 as a difference frequency of f osc - is f Hilf, In Germany Frequency then always between the HF picture and HF sound carrier. So there is z. B. when selecting channel 10 in band 111 of TV reception frequency range a characteristic frequency of 213 MHz with a set oscillator frequency of 249.15 MHz of the tuner oscillator 1.

Die Kennfrequenz von 213 MHz ergibt zusammen mit der Oszillatorfrequenz von 249,15 MHz eine Zwischenfrequenz von 36,15 MHz am Ausgang des Tuners 1. Diese Zwischenfrequenz liegt in der Bandmitte des Zwischenfrequenzkanals und gelangt über einen Bandpass 13 auf den im Empfangsgerät vorhandenen Zwischenfrequenzbaustein 14. Dieser Baustein besitzt einen Synchron-Demodulator, für den die Referenzfrequenz an einem außen angeschalteten Referenzschwingkreis 15 erzeugt wird. Die Referenzschwingkreis besteht aus dem Kondensator 16 und der Spule 17 und ist für den normalen Empfangsfall auf 38,9 MHz den Bildzwischenfrequenzträger abgestimmt.The characteristic frequency of 213 MHz together with the oscillator frequency of 249.15 MHz results in an intermediate frequency of 36.15 MHz at the output of the tuner 1. This intermediate frequency lies in the middle of the band of the intermediate frequency channel and reaches the intermediate frequency module 14 present in the receiving device via a bandpass 13. This module has a synchronous demodulator for which the reference frequency is generated at an externally connected reference resonant circuit 15. The reference resonant circuit consists of the capacitor 16 and the coil 17 and is tuned to 38.9 MHz for intermediate reception, the intermediate image frequency carrier.

Während des automatischen Abgleichs wird vom Mikroprozessor 5 gesteuert der Referenzschwingkreis 15 auf die niedrigere Referenzfrequenz 36,15 MHz umgeschaltet, indem über die Schaltstufe 18 ein Kondensator 19 parallelgeschaltet wird.During the automatic adjustment, the reference resonant circuit 15 is switched to the lower reference frequency 36.15 MHz, controlled by the microprocessor 5, in that a capacitor 19 is connected in parallel via the switching stage 18.

Am AGC-Ausgang der Zwischenfrequenzstufe 14 wird am Kondensator 20 eine Meßspannung abgenommen, die über eine Sample-and-hold-Schaltung 21 gewandelt dem Mikroprozessor zugeführt wird, welcher solange die Abstimmspannung erhöht, bis ein Maximum der Meßspannung am AGC-Ausgang erreicht ist.At the AGC output of the intermediate frequency stage 14, a measuring voltage is taken from the capacitor 20, which is converted via a sample-and-hold circuit 21 and fed to the microprocessor, which increases the tuning voltage until a maximum of the measuring voltage at the AGC output is reached.

Der Mikroprozessor erhöht über den D/A-Wandler 23 die Abstimmspannung in Stufen bis die S/H-Schaltung einen optimalen Abgleich anzeigt. Für diesen optimalen Abgleich wird ein digitales Wort abgespeichert. Die übrigen Kreise werden auf die gleiche Weise vom Mikroprozessor 5 gesteuert nacheinander abgeglichen. Es ist notwendig während des automatischen Abgleichs die Zeitkonstante der automatischen Verstärkungsregelung zu verkleinern. Dies geschieht dadurch, daß über eine Schaltstufe 24 der für eine große Zeitkonstante maßgebliche Kondensator 25 abgeschaltet wird.The microprocessor increases the tuning voltage in stages via the D / A converter 23 until the S / H circuit indicates an optimal adjustment. A digital word is stored for this optimal comparison. The other circles are controlled in succession in the same way by the microprocessor 5. It is necessary to reduce the time constant of the automatic gain control during the automatic adjustment. This is done by switching off the capacitor 25, which is relevant for a large time constant, via a switching stage 24.

In Fig. 2 ist gezeigt, wie die Frequenzlage der erzeugten Kennfrequenz K entsteht. Dies sei am Beispiel des Kanals 10 erläutert.2 shows how the frequency position of the generated characteristic frequency K arises. This is explained using the example of channel 10.

Nach Anwahl des Kanals 10 stellt sich die Tuneroszillatorfrequenz auf 249,15 MHz ein. Der Bildträger des Empfangssignals liegt bei 210,25 MHz der Tonträger bei 215,75 MHz. Es wird eine Kennfrequenz K erzeugt, die zwischen Bildträger und Tonträger liegt und um 36,15 MHz niedriger als die eingestellte Oszillatorfrequenz ist. Diese Frequenz K stellt also die Differenz von fose und 36,15 MHz dar.After selecting channel 10, the tuner oscillator frequency is set to 249.15 MHz. The image carrier of the received signal is 210.25 MHz and the sound carrier is 215.75 MHz. A characteristic frequency K is generated which lies between the image carrier and the sound carrier and which is 36.15 MHz lower than the set oscillator frequency. This frequency K thus represents the difference between free and 36.15 MHz.

In Fig. 3 ist gezeigt, wie der Referenzkreis 15 von seiner Resonanzfrequenz 38,9 MHz auf 36,15 MHz umgeschaltet wird.In Fig. 3 it is shown how the reference circuit 15 is switched from its resonance frequency 38.9 MHz to 36.15 MHz.

In Fig. 4 ist der Verlauf der AGC-Spannung dargestellt, der ein genaues Abbild des Referenzkreises nach Fig. 3 ist.FIG. 4 shows the course of the AGC voltage, which is an exact image of the reference circuit according to FIG. 3.

Claims (2)

1. An adjustment system working automatically for the tuner of a television receiver having a tuner oscillator (10) which can be tuned by a phase-locked loop (PLL), wherein an auxiliary frequency (8) is connected to the aerial input during the automatic adjustment and the individual radio-frequency tuned circuits (2, 3, 4) of the tuner (1) are adjusted in succession to a maximum output voltage in that tuning voltage values are applied in succession, in digital steps, controlled by a microprocessor (5), to the capacitance diodes present in the radio-frequency tuned circuits (2, 3, 4), and the increase in the tuning voltage values is interrupted when a maximum value, detected by an evaluation circuit, is reached at the output, characterised in that a frequency which results from the difference between the set tuner oscillator frequency (OSC) and the arithmetical mean of the i.f. picture-carrier frequency (BT) and the sound-carrier frequency (TT) is selected as the auxiliary frequency (K), that during the automatic adjustment operation, the i.f. component (14) present in the set is used as an evaluation circuit in that the output signal for the automatic gain control (AGC) is fed as a measuring voltage to a sample-and-hold circuit (21) which is connected to an input of the microprocessor (5), and that the reference oscillatory circuit necessary in the i.f. component (14) is switched over, in its resonant frequency to a frequency which corresponds to the arithmetical mean of i.f. picture-carrier frequency (BT) and i.f. sound-carrier frequency (TT).
2. An adjustment system working automatically according to Claim 1, characterised in that, during the adjustment operation, a capacitor (20, 25), which is connected to the AGC output of the i.f. component (14) and is decisive for the time constant of the automatic gain control, is switched over to a lower value, controlled by the microprocessor (5).
EP84114292A 1983-12-27 1984-11-27 Tuning system for a television receiver Expired - Lifetime EP0148389B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84114292T ATE50894T1 (en) 1983-12-27 1984-11-27 TUNING SYSTEM FOR A TELEVISION RECEIVER.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3347132 1983-12-27
DE3347132A DE3347132C1 (en) 1983-12-27 1983-12-27 Automatic adjustment system for a tuner of a television receiver

Publications (3)

Publication Number Publication Date
EP0148389A2 EP0148389A2 (en) 1985-07-17
EP0148389A3 EP0148389A3 (en) 1987-04-01
EP0148389B1 true EP0148389B1 (en) 1990-03-07

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EP84114292A Expired - Lifetime EP0148389B1 (en) 1983-12-27 1984-11-27 Tuning system for a television receiver

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US (1) US4956711A (en)
EP (1) EP0148389B1 (en)
JP (1) JPS60158713A (en)
AT (1) ATE50894T1 (en)
DE (2) DE3347132C1 (en)
DK (1) DK163622C (en)
FI (1) FI89430C (en)
NO (1) NO164330C (en)

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DE3303711C2 (en) * 1983-02-04 1985-01-24 Deutsche Thomson-Brandt Gmbh, 7730 Villingen-Schwenningen Voting unit for telecommunications equipment

Also Published As

Publication number Publication date
FI844843L (en) 1985-06-28
DK163622B (en) 1992-03-16
FI89430B (en) 1993-06-15
ATE50894T1 (en) 1990-03-15
NO164330B (en) 1990-06-11
NO164330C (en) 1990-09-19
EP0148389A3 (en) 1987-04-01
EP0148389A2 (en) 1985-07-17
NO845128L (en) 1985-06-28
DK163622C (en) 1992-08-17
JPH0572767B2 (en) 1993-10-13
FI844843A0 (en) 1984-12-07
JPS60158713A (en) 1985-08-20
FI89430C (en) 1993-09-27
US4956711A (en) 1990-09-11
DK623284D0 (en) 1984-12-21
DE3347132C1 (en) 1985-07-04
DK623284A (en) 1985-06-28
DE3481573D1 (en) 1990-04-12

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